Woodworm in timber frame house - How to defend against it?

hello forum,

to my alarm I have discovered reddish-brown beetles in the house for several days.
At first I simply ignored them but meanwhile we kill 10-20 every day.
After researching on the internet I was able to narrow down the species.
All species belong to the woodboring beetles whose larvae love to eat wood.

The problem is as follows...
We have a timber frame house and now you start to wonder why this insect is here with us.
Our house is sealed towards the floor slab so nothing can come in there.
Also through the windows that is not possible since we almost only run the ventilation system, so the windows stay closed.
The beetle lays eggs in the wood and the larvae eat it and when they are done the beetles come out.
The larvae need 1-8 years to develop into a beetle.
The house is not even 2 years old.
This means for me that the larvae in the wooden structure of the house were already present during manufacturing.
We have no damaged wooden furniture etc. and also on the roof no damage can be detected.
On Tuesday I am going to a pest control expert with the specimens and he will tell me what it is.

What if it is a bread beetle, carpet beetle?
Are there any cases known in this respect?
Who is to blame?
Theoretically it is not possible that we are responsible ourselves because of the development time of the beetle and the age of our house.

Maybe it is a false alarm but something is not right.
Best regards

The pest control operator says it is a Brown Furniture Beetle or an American Furniture Beetle. The ball is rolling...

Can the expert narrow down certain types of wood that are affected? To my knowledge, sapwood beetles preferably infest hardwood with a high sapwood content. Wooden (frame) houses are usually built from softwood, as hardwood is not suitable as construction wood.

That might help in searching for the origin of the critters.

Thank you very much for the hint.

He also said that it could be a rice flour beetle and that these two species look very similar. We searched through all the food and found nothing. If you crush the beetles, your hand smells like fresh wood.

Wow, what a nightmare.

Are there any holes visible in the wood anywhere?

We had wood wasps.
They came in through birch trees that we have as decoration.
That was quite a shock at first.